1. Field of the Invention
The invention relates generally to golf clubs and, more particularly, to putter heads.
2. Description of Related Art
In recent years, a great amount of attention has been given by golf club designers, engineers, and manufacturers towards moving the weight and the center of gravity (CG) towards the polar extremes, increasing the moment of inertia (MOI) of the putter head, so that the putter twists less on off-center hits and therefore is more forgiving and more accurate on miss-hits. Such polar weighted putter heads increase the effective hitting area, commonly referred to as the “sweet spot,” and, therefore, are more forgiving on miss hits where the golf ball is not struck in the center of the clubface.
Various manufacturing techniques have been attempted to achieve a golf club possessing the above features, i.e., increasing the size of the MOI and the sweet spot or effective hitting area. These techniques have included placing dense weight in the polar extremes of the heel and toe of a blade-type putter, which are generally narrow from face to back. However, blade-type putter heads are not as forgiving or have as high a MOI as mallet type putters, whose large mass and rearward CG makes them more forgiving.
The mallet-type head geometry usually provides for a larger head and larger footprint than that of a blade-type putter, and much of the mass is spread out throughout the area of the head. Such large mallet heads are not visually appealing to many golfers who prefer blade-type putters.
Also, depending on the placement of, and type of hosel or shaft connection, including how much offset and where the hosel or shaft is connected, as well as variables with the user's stroke mechanics, these large mallet heads can be awkward to swing and rotate properly in concert with the elliptical path of the stroke plane. Too large an amount of mass in an aft-back location, too far away from the axis of the shaft can cause many golfers to have to overly manipulate the putter to maintain a proper face to plane relationship, or cause the putter to be pushed off the stroke plane on the backstroke. This in turn can negatively affect the resultant forward stroke, the position and alignment of the putter head at contact, and therefore the accuracy and consistency of the results with such a putter design.
It should be noted that the weight and balance specifications and requirements of each putter are as individual as the style and specifications of the golfers themselves.
Blade putters, including cavity back flange type putters and thin or half-mallets, are generally easier for more golfers to swing correctly on a stroke plane without unwanted manipulation, because the mass and center of gravity of the club head are usually positioned more proximate to the axis of the shaft. Therefore, many golfers are more comfortable with, have more experience with and are more confident using blade-type putters, even though the deeper CG and higher MOI of a mallet-type putter is often more forgiving. However, blade type putters generally have very short sighting lines due to their thin width face to back, and therefore are not as easy to align as larger mallets that contain longer sight lines or other indicia.
Furthermore, it is known that many golfers get tired of their putter when their performance with it is less than desirable. Switching to a new putter often brings more success, at least initially, as the golfer tends to concentrate more and use new neural pathways to perform the stroke. It is believed that the new sensations, including optical sensations, play a role in the player's performing better with the new putter. However, it is proven that most golfers putt better when their putter is properly fit for all their physical properties of length, lie, loft, offset, weight of the individual components, grip style and size and the like.
Blade-type putters are also usually limited in the amount of weight that can be placed in the head due to their dense, thin structures. Placing additional weights onto these heads, such as in the cavity, on the heel or toe or soles can negatively affect the appearance, balance and CG and performance of the putter. Lead weight strips can also be dislodged through use and from interference with the other clubs in the bag when so exposed on the exterior surfaces.
Other prior art teaches attachment of appendages to aid in alignment. However, the governing bodies have rules prohibiting any “attachments to the head,” other than lead tape, which is grandfathered in as traditional. These rules have allowed multi-piece heads, so long as all the pieces are fixed. It is commonly understood that weights, such as screws and the like, are allowable as long as they are affixed “into” the head, versus “onto” the head.
None of the known prior art teaches the ability or a mechanism to fit or customize the Center of Gravity of a traditionally styled putter head, within the rules of golf, to suit an individual golfer's stroke mechanics and the resultant dynamic center of percussion, nor the ability to customize the length, shape or alignment indicia of a back-weight member to suit an individual golfer's preferences and needs for alignment shape and indicia.
In one prior art attempt to make a putter that achieves some of these desired advantages, a multi-piece putter head was provided having a putter head portion with an opening from front to back, and having a through-head insert having a front face for striking the ball and a rear portion extending through the opening rearwardly. In this prior attempt, however, the insert was retained solely by means of an interference fit between the through-head insert and the opening through the putter head portion and thus could be dislodged by rough handling or some conditions of play. (Although the insert can generally have an oval shape, rather than round, this interference fit can be regarded as causing the putter head portion to impose a force on the insert that is generally parallel to the striking face of the through-head insert and generally inwardly oriented.)
This means of securing the through-head insert in the putter head portion has disadvantages. The amount of the interference fit force is very sensitive to small changes in dimension of the through-head insert, the putter head portion and its opening, thus making it difficult to manufacture the multi-piece putter consistently with the same interference fit force between the through-head insert and the putter head portion in all putters under all conditions. Thus, in some cases, it is possible that the force will be insufficient to hold the parts together if the putter head is dropped or otherwise roughly handled, for example, or to avoid undesirable relative vibration between through-head insert and the putter head portion under all playing conditions. Furthermore, it is possible that the interference force can also tend to bow out the striking face to a small degree, which could interfere with manufacturing procedures as well as risking changing the flatness of the striking face.